A patterned sapphire substrate (PSS) is a sapphire substrate with a patterned surface formed via photoetching and etching. The patterned substrate, on the one hand, can effectively reduce dislocation density of the epitaxial structure and improve lattice quality and evenness of the epitaxial material, thereby enhancing the internal quantum light-emitting efficiency; on the other hand, the array pattern structure increases light scattering and changes light route of the light emitting diode, thus optimizing chance for light-emitting.
Existing patterned substrates generally have a large-size C surface (i.e., (0001) surface of the sapphire). The threading dislocation of the C surface is prone to extend to the quantum well of light emitting diode, causing non-radiative recombination. The Chinese Patent No. CN102244170B discloses a patterned sapphire substrate with photonic quasi-crystal, with the attempt to cut the area proportion of the exposed C surface of the patterned structure on the entire sapphire substrate. However, as the patterned structure is composed of a series of photonic crystals, the gap 205 is bound to exist between photonic crystals, i.e., a C surface exists.